Methods and compositions for use in the prevention, treatment and/or alleviation of cancer

ABSTRACT

The ratio of zinc and cadmium is of significance for error-free proliferation and differentiation of cells. An understanding of the role of cadmium in the etiology of cancer offers possibilities to gain a better understanding of cancer as well as possibilities to prevent, treat and/or alleviate cancer. The concentration of Zn(II) in fetal serum, human serum from umbilical cord blood or healthy donors, and in avian serum including intact eggs and egg products has significance for the reliability and repeatability of cell and tissue culture method using said serum, or serum containing products, or eggs. Disclosed is a method in the manufacture of serum products, in particular serum products intended for use in in vitro culture of mammalian cells or tissues, wherein the concentration of Zn(II) is determined, and preferably adjusted to a desired interval. Different products consisting of or containing serum or serum fractions are also disclosed.

RELATED APPLICATION DATA

This application is a divisional application of U.S. patent applicationSer. No. 15/409,754, filed Jan. 19, 2017, which claims the benefit ofSwedish Application No. 1650058-9 filed Jan. 19, 2016, the disclosuresof which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present disclosure investigates the etiology of cancer, and proposesnew principles of preventing, treating or alleviating cancer inmammalian subjects.

The present disclosure also relates generally to improvements in theproduction and use of blood products, serum products, and cell growthmedia, in particular to such products consisting or comprising fetalserum of different origin, but not limited thereto. Avian serum and eggproducts are also relevant growth media, which can be subjected tomodifications based on the findings and methods disclosed herein.

Blood products intended for administration to human patients, such aswhole blood products, serum and plasma products, and blood fractions,are also comprised herein.

BACKGROUND

Cancer is a collective term for diseases caused by an uncontrolleddivision of cells in the body. Frequently the term refers specificallyto the malignant growth or tumor resulting from such uncontrolleddivision of cells. Historical records show that cancer has scared andeluded humanity since ancient times. In the world of today, with betterhealthcare and increasing lifespans, the prevalence of cancer seems tohave increased. While some forms of cancer can be cured, the outcome isfar from certain, and cancer still remains an enigmatic and frighteningdiagnosis.

In his award-winning book “The Emperor of All Maladies: A Biography ofCancer”, Siddhartha Mukherjee, Ph.D., M.D. states that “it is unclearwhether an intervention that discriminates between malignant and normalgrowth is even possible. Perhaps cancer, the scrappy, fecund, invasive,adaptable twin to our own scrappy, fecund, invasive, adaptable cells andgenes, is impossible to disconnect from our bodies. Perhaps cancerdefines the inherent outer limit of our survival. As our cells divideand our bodies age, and as mutations accumulate inexorably uponmutations, cancer might well be the final terminus in our development asorganism.”

The present inventor however disagrees with the above conclusion.Instead, the present inventor notes that there is a phase in thedevelopment of mammals when cell proliferation is extremely fast andefficient, but during which there are very few if any occurrences ofcancer. This is the gestation period, i.e. the time in which a fetusdevelops, beginning with fertilization and ending with birth. Theduration of this period varies between species. In humans, the gestationperiod is about nine months. Smaller, short lived mammals generally havea shorter gestation period, e.g. about 19 to 21 days for mice, and about31 days for rabbits. Conversely, larger, long lived mammals tend to havea longer gestation period, e.g. about 21 months for elephants, and about14 to 16 months for sperm whales.

During the gestation period, an extremely rapid cell differentiation andproliferation takes place. It appears that also others have noticedthis, for example Vincent T. DeVita Jr. and Elizabeth DeVita-Raeburn intheir book “The Death of Cancer: After Fifty Years on the Front Lines ofMedicine, a Pioneering Oncologist Reveals Why the War on Cancer isWinnable—and How we can Get There” (Sarah Crichton Books, 2015) concludethat “embryonic cells have only nine months to make a baby: they mustwork very fast”. Nevertheless, very few “mistakes” happen during thisfast work. Obviously, there is either an absence of disturbing factors,or very effective control and repair mechanisms at work. The presentinventor has accepted the challenge to identify these, and to put themto use in combatting cancer.

The present inventor is of course aware of the fact that there areinstances where a fetus develops neuroblastoma, leukemia or teratoma,but these diseases are extremely rare. As the metabolism and developmentof the mammalian fetus is regulated by the same genes as in the adultmammal, it becomes interesting to determine what conditions or factors,molecular or other, differ between the period spent in utero, and thelife post partum.

Additionally, the fast and well-regulated proliferation phase must thenbe quickly and adequately down-regulated. The similarities anddifferences between the well-regulated fast proliferation in theembryonal phase and the unregulated, pathological proliferationencountered in various forms of cancer have been the subject ofextensive research. A number of relevant articles are listed in theattached list of references, incorporated herein by reference.

Understanding the factors regulating both benign and malignant cellproliferation is crucial for the capability to predict, detect and treatcancer. Important work is being performed in vitro, in cell culture.More specifically, the techniques of in vitro cell, tissue and organculture is of great importance to pure and applied science, medicine andindustry. Amongst others, it is considered a major replacementalternative in animal experimentation. This use poses high requirementson the reliability and repeatability of the experiments.

Cells require a complex environment in order to survive and proliferatein vitro. Therefore, in order to successfully culture cells in vitro,culture medium needs to be added to the cells. Usually, the culturemedium contains animal serum as this contains basic components, such ashormones, growth factors, essential elements, proteins, amino acids,nucleic acids, etc. The most common type of serum used for cell growthis fetal bovine serum (FBS), also known as fetal calf serum (FCS). Serumfrom other species is also available.

FBS is obtained from fetuses harvested in abattoirs from healthy damsfit for human consumption. Sera is also available from other species,such as horse, cat, dog, rabbit, et cetera, and used primarily whencells from said species are cultured. In the cell culture, the serumprovides a source of a wide variety of macromolecular proteins, lowmolecular weight nutrients, carrier proteins for water-insolublecomponents, and other compounds necessary for in vitro growth of cells,such as hormones and attachment factors. Serum also adds bufferingcapacity to the medium and binds or neutralizes toxic components. Sofar, attempts to replace serum entirely with serum-free medium have metonly with limited success. Serum must therefore be considered to be araw material or reagent of crucial importance for research andmanufacture within the entire life science sector.

In the serum manufacturing process, whole blood is aseptically collectedand allowed to clot. Once the serum has been separated from the clot, itis pooled and frozen. Selected batches are then thawed, tested forendotoxins and hemoglobin content and only the accepted material ispooled and thoroughly blended. The pooled sera are then sterile filteredusing a sequence of pre-filters and membrane filters. For example, a 0.1micron sterilizing grade filter or a series of such filters, can beused. After filtration, the serum is aseptically dispensed into bottlesensuring the sterility of the final product.

Using fertilized eggs as growth medium is an alternative to animal sera,used in large scale methods, for example in the production of forexample of vaccines, and antibodies, for prophylactic, therapeutic anddiagnostic purposes.

There are several manufacturers of animal sera for cell culturepurposes, and all take great care to ensure that the products meet highrequirements with regard to sterility, purity, and other qualitycriteria. One manufacturer lists the following properties, shown inTable 1 below:

TABLE 1 Quality control of serum products Physical and chemical tests:Electrophoretic pattern, pH, osmolarity, total proteins, albumin, IgG,hemoglobin, globulins Biochemical tests: Alanine transaminase (ALT),alkaline phosphatase, aspartase aminotransferase (ast), bilirubin -total, bilirubin - direct, blood urea nitrogen (BUN), calcium, chloride,cholesterol, creatinine, creatinine kinase (CK), gamma-glutamyltransferase (GGT), glucose, high density lipoproteins (HDL), low densitylipoproteins (LDL), inorganic phosphorous, potassium, sodium,triglycerides (TG), and uric acid Microbiological tests: Sterility test(bacterial and fungal sterility tests according to current USP)Mycoplasma contamination (according to CFR) Viral contamination(according to CFR for bovine viral diarrhea (BVD), infectious bovinerhinotracheitis (IBR), and parainfluenza type 3 (PI3) Viral antibodies(determination of titer of antibodies to BVD, IBR and PI3) Endotoxins(Limulus amebocyte lysate (LAL) test using kinetic turbidimetric method)

The manufacturers also test the stability and biological performance,i.e. checking the efficacy of the serum in promoting cell growth.However, as a precaution, manufacturers frequently underline that serumis a biological material, an undefined mixture of components in whichthe composition varies from one lot to another, and that some cell typesare sensitive to variations in serum performance. As a consequence,customers are encouraged to evaluate serum samples using their ownculture system and cells. In the meantime, the manufacturer reservesquantities of the specific lots until the testing is complete. In thisway, a customer may choose the serum best suited for his particularapplications (Product brochure E49/2 07/15 from Biological IndustriesIsrael Beit Haemek Ltd., Kibbutz Beit Haemek, 25115, Israel).

Further, a large range of drugs and reagents used in therapy anddiagnosis are currently synthesized using cell culture methods in largescale manufacturing facilities. Cell culture is also widely used in thevaccine industry, as well as in the production of antibodies. Lately,cell culture has also been used in the production of tissues and evenorgans, for use in reconstructive surgery and transplants. All theseuses of serum and serum products involve extremely high requirements onreliability and repeatability.

The present inventor has recognized a need for improving the quality andreliability of cell culture media and cell culture methods. He has alsoset out to investigate the causative factors behind cancer, aiming atfinding new approaches to prevent, alleviate or treat cancer.

SUMMARY

The present inventor has studied the biological roles of two metals,zinc and cadmium, and their behavior, distribution and ratio in thebody. One important finding is that while zinc passes through theplacenta barrier, into the developing fetus, a healthy placenta willeffectively bind cadmium. As a consequence of this finding, the inventorpostulates that it is extremely important to analyze and be aware of theconcentration of these two metals, and the ration between them, bothwhen studying cancer, and when treating cancer. It is for exampleimportant that blood products which are administered to a patient do notcontain any cadmium, or as little cadmium as possible. Similarly, it isof great importance to know the concentration of these metals in cellculture media, for example when studying cell proliferation.

Without wishing to be bound by theory, the inventor contemplates thatthe cancer promoting effect of cadmium is liked to the metal's effect onthe tight junctions, the closely associated areas of two cells whosemembranes join together forming a virtually impermeable barrier tofluid. This is a type of junctional complex present only in vertebrates.The inventor contemplates that disruption of the tight junction promotesmetastasis.

The present inventor has also surprisingly found that the concentrationof metals, in particular the concentration of Zn(II),variessignificantly in serum products of different batches and from differentanimal origin. At the same time, the present inventor postulates thatthe concentration of metals, in particular Zn(II), has a significantinfluence inter alia on the proliferation of cells cultured in mediacontaining serum products. This makes it important that theconcentration of metals, in particular the concentration of Zn(II), isknown, and it becomes equally important that the concentration of Zn(II)is adjusted to a desired level.

The term “adjusted” can here mean that the concentration is increased orreduced, depending on the initial level and the desired level. This isrelevant for serum products intended to be used as such use in therapy,as well as serum product intended for use in the manufacture of drugs,such as antibodies or vaccines, or reagents, such as reagents used indiagnostic assays and kits, e.g. antibodies. This is also relevant forserum products for use in the culture of cells, tissues or even organs,for use in therapy, e.g. reconstructive surgery or transplants.

One aspect of the invention relates to the importance of knowing thetrue Zn(II) concentration in a fetal serum product intended for suchuse. Consequently, one embodiment of the invention concerns a methodstep in the manufacture of serum products, in particular serum productsintended for use in in vitro culture of cells or tissues, wherein theconcentration of Zn(II) is determined. Preferably the concentration ofZn(II) in the serum is adjusted to a desired interval, more preferablyreduced or increased in correlation to other culture parameters inquestion.

According to a preferred embodiment, the concentration of Zn(II) isadjusted to an interval of about 50 to about 200 μmol/l in the finalserum product. According to an alternative embodiment, the concentrationof Zn(II) is adjusted to about 50 μmol/l in the final product.

According to yet another alternative embodiment, the concentration ofZn(II) is adjusted to an interval of less than about 15 μmol/l,preferably less than about 10 μmol/l, more preferably less than about 5μmol/l in the final serum product.

According to one embodiment, the adjustment of the concentration ofZn(II) is performed by mixing fetal serum of at least two differentserum batches having different concentrations of Zn(II) in a ratio suchthat the final concentration of Zn(II) is in an interval of about 50 toabout 200 μmol/l in the final serum product.

According to an embodiment, the adjustment of the concentration ofZn(II) is performed by subjecting fetal serum to a separation method,e.g. ultracentrifugation and removing the formed pellet.

According to an embodiment, freely combinable with all the aboveembodiments, the fetal serum is fetal serum from a mammal chosen fromcattle, pig, horse, goat, cat, dog, and rabbit. According to a specificembodiment, when human serum is involved, this is human umbilical cordserum or serum obtained from healthy donors.

Another aspect of the invention is the surprising finding relating tothe significance of exosomes present in fetal serum, their content ofZn(II) and the possibilities it opens for adjusting the Zn(II) contentof serum products. Not only are there indications (see the Examplessection and the analysis results) that the exosomes and possibly othermicro and nano particles in the serum contain the main portion of theZn(II) present in the serum, there are also indications that exosomesplay a significant role in the signaling between cells, and in theproliferation of cells of different origin. It is contemplated thatexosomes function as transporters and reservoirs of Zn in the serum, andthat this function can be utilized to optimize both the quality of serumproducts and cell culture conditions in various applications.

The inventor has also found indications that the exosomes are capable ofabsorbing cadmium, and that the exosomes can be an important carrier ofcadmium in blood and serum products. This finding makes it possible toreduce the cadmium content in blood and serum products by removingcontaminated exosomes. According to an embodiment, exosomes with a highconcentration of cadmium can be removed and replaced by exosomescontaining zinc.

Another aspect of the invention relates to products where serum iscollected and the exosomes separated, forming a range of productswithout or with specified concentrations of exosomes, andcorrespondingly specified, desired concentrations of Zn(II). Preferablyserum is collected from different species, which allows the productionof species-specific products, such as bovine, avian, and human serumproducts and exosome fractions. A preferred embodiment relates to thecollection of umbilical cord blood and the preparation of human serumfractions with specified concentrations of exosomes, and correspondinglydifferent, desired concentrations of Zn(II).

The present inventor has realized that the concentration of exosomes aswell as the concentration of Zn(II) needs to be known and preferablyadjusted to pre-set desired levels in order to guarantee reliable andconsistent result in manufacturing and research applications where fetalserum products are used.

Thus, according to another embodiment, also freely combinable with allthe above embodiments, the concentration of exosomes in the serum isdetermined, and the concentration in the final product is adjusted to avalue within a desired interval.

Yet another embodiment, also freely combinable with all the aboveembodiments, makes available a method step in the manufacture or thepreparation of a fetal serum product based on fetal serum of a specificspecies, wherein the diameter of the exosomes is determined, and/or theconcentration of Zn(II) in the exosomes in serum from said specificspecies is determined, whereupon the concentration of Zn(II) in thefinal product is adjusted, i.e. increased or reduced, to a value withina desired interval. This can be done by separating and removing a Zn(II)containing fraction, e.g. an exosome fraction, or by adding suchfraction, in order to achieve the desired concentration.

Similarly, the concentration of cadmium can be reduced by removingcontaminated exosomes, and replacing them with healthy, non-contaminatedexosomes.

An important aspect of the invention is thus the provision of new andimproved fetal serum products, including human umbilical cord serum orhealthy donor serum, inter alia a fetal serum product manufacturedaccording to a method or methods including one or more of the steps setout in the above embodiments.

One example is a fetal serum product having a concentration of Zn(II)adjusted to an interval of about 50- about 200 μmol/l. Another exampleis a fetal serum product having a concentration of Zn(II) adjusted toabout 50 μmol/l. A preferred example is a fetal serum product having aconcentration of Zn(II) adjusted to an interval of less than about 15μmol/l, preferably less than about 10 μmol/l, more preferably less thanabout 5 μmol/l in the final product.

An important aspect is that the concentration of Zn(II) should bedetermined and known before the product is used. One embodimenttherefore relates to a fetal serum product, preferably but notnecessarily manufactured using one or more of the above steps, whereinthe concentration of Zn(II) in said product has been determined and isindicated on the package or in the accompanying product data sheet.

Yet another aspect of the invention relates to methods for cell ortissue culture, regardless if the cell or tissue culture is part of aproduction method, a diagnostic method, therapy or research. Oneembodiment of this aspect is a method for in vitro cell or tissueculture using a culture medium containing a fetal serum product, whereinthe concentration of Zn(II) in the culture medium is determined, andadjusted to a desired level.

In the above embodiment, preferably the cells to be cultured are humancells, and the concentration of Zn(II) in the culture medium is adjustedto a value in the interval of 50- about 200 μmol/l, more preferably theconcentration of Zn(II) in the culture medium is adjusted to about 50μmol/l. More preferably the concentration of Zn(II) in the culturemedium is adjusted to a value within an interval of less than about 15μmol/l, preferably less than about 10 μmol/l, more preferably less thanabout 5 μmol/l in the final product.

Another aspect of the invention relates to methods for in vitro cell ortissue culture using a culture medium containing a fetal serum product,wherein the concentration of Zn(II) in the culture medium is determined,adjusted to a selected level, and maintained at said level during theduration of the cell or tissue culture and/or when repeating saidculture.

Yet another aspect of the invention concerns avian serum products, andin particular egg white and egg yolk. The present inventor has foundthat eggs contain higher amounts of Zn(II) than mammalian serum. Theconcentration of Zn(II) in egg yolk can be in the interval of 50-70micro molar. The inventor postulates that it is of considerablesignificance that the concentration of Zn(II) is known in order toensure repeatability of the culture methods where avian serum or eggproducts are used. Further, it is also preferred that the concentrationof Zn(II) is adjusted to a desired level also in avian serum and/oreggs. This can be achieved for example by adjusting the feed, or byadding a species specific Zn(II) containing fraction to an avian serumproduct or to eggs.

An embodiment of the invention therefore relates to avian serum productsmanufactured according to the methods or method steps disclosed herein,mutatis mutandis, i.e. with necessary modifications.

One embodiment is thus an avian serum product having a concentration ofZn(II) adjusted to an interval of about 50- about 200 μmol/l. Preferablysaid avian serum product has a concentration of Zn(II) adjusted to about50 μmol/l.

According to a preferred embodiment, the avian serum product has aconcentration of Zn(II) adjusted to an interval of less than about 15μmol/l, preferably less than about 10 μmol/l, more preferably less thanabout 5 μmol/l in the final product.

A particular embodiment is an avian serum product wherein theconcentration of Zn(II) in said product has been determined and isindicated on the package or in the accompanying product data sheet.

Another embodiment of said aspect is a method for in vitro cell ortissue culture using a culture medium containing an avian serum product,wherein the concentration of Zn(II) in the culture medium is determined,and adjusted to a desired level. Preferably the concentration of Zn(II)in the culture medium is adjusted to a value in the interval of 50-about 200 μmol/l. More preferably the concentration of Zn(II) in theculture medium is adjusted to about 50 μmol/l.

Yet another embodiment is the use of avian serum and/or eggs in celland/or tissue culture, or in the manufacture of antibodies and vaccines,including a method step wherein Zn(II) enriched serum or a serumfraction is added to a fertilized egg using known methods forinoculating eggs. This Zn(II) enriched serum or a serum fraction isspecies specific, i.e. when added to hen eggs, hen serum is used, andwhen added to duck eggs, duck serum is used. The Zn(II) concentration ofthe enriched serum or fraction is determined and the serum or fractionis also subjected to necessary quality control, as known to personsskilled in the art.

Further, according to an embodiment freely combinable with the aboveaspects and embodiments, the cells to be cultured are human cells, andthe concentration of Zn(II) in the culture medium is adjusted to a valuewithin an interval of less than about 15 μmol/l, preferably less thanabout 10 μmol/l, more preferably less than about 5 μmol/l in the finalproduct/l. In the case of eggs, the concentration of Zn(II) can beinfluenced by adjusting the composition and amount of feed given to thebirds, e.g. hens or ducks.

Another aspect is a novel method for in vitro cell or tissue cultureusing a culture medium containing an avian serum product, characterizedin that that the concentration of Zn(II) in the culture medium isdetermined, adjusted to a selected level, and maintained at said levelduring the duration of the culture and/or when repeating said culture.

Another embodiment is the use of species specific Zn(II) enriched seraor fractions, e.g. species specific exosome fractions in cell, tissueand organ cultures. Such species-specific sera or serum fractions can bemanufactured in cell culture under species specific conditions.

Another object of the present invention is to provide methods for theprevention, treatment, and alleviation of cancer in mammalian subjects,based on the inventor's understanding of the role of cadmium in theinduction of cancer.

This and other objects are achieved by the aspects and embodimentsdefined in the independent claims, incorporated herein by reference.Further advantageous embodiments have been specified in the dependentclaims, incorporated herein by reference.

SHORT DESCRIPTION OF THE FIGURES

Different aspects and embodiments will be disclosed in closer detail inthe following description, examples and claims, with reference to theattached figures in which:

FIG. 1 shows an autoradiograph image of a pregnant mouse, showing thedistribution of the radioactive zinc isotope ⁶⁵Zn. The white dots in theembryonal sack indicate an enrichment of the isotope. This proves thatzinc is capable of passing through the placenta.

FIG. 2 shows a detailed view, focusing on the uterus containing multiplefetuses. Again, an enrichment of ⁶⁵Zn can be seen.

FIG. 3 shows another autoradiograph image of a pregnant mouse that hasbeen subjected to the radioactive cadmium isotope ¹⁰⁹Cd. In thispicture, the enrichment of cadmium is shown as black. It can be seenthat the cadmium isotope is enriched in the liver and kidney, and tosome extent in placental tissue. However, no cadmium has passed throughthe placenta into the fetus.

DESCRIPTION OF EMBODIMENTS

Before the present invention is described, it is to be understood thatthe terminology employed herein is used for the purpose of describingparticular embodiments only and is not intended to be limiting, sincethe scope of the present invention will be limited only by the appendedclaims and equivalents thereof.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise.

Also, the term “about” is used to indicate a deviation of +/−2% of thegiven value, preferably +/−5%, and most preferably +/−10% of the numericvalues, where applicable.

The term “fetal serum products” is used to indicate both fetal serum assuch, when marketed as a reagent or substrate for use in production,diagnosis, therapy or in research applications, as well as products forsuch use, comprising fetal serum.

In relation to humans, the source of serum and exosomes is preferablyumbilical cord blood, but is it not excluded that blood products fromhealthy donors can be used.

The general understanding until now is that fetal bovine serum (fetalcalf serum) is the most suitable serum-supplement for in vitro cellculture of eukaryotic cells and tissues. This is due to it having a verylow level of antibodies and containing more growth factors, allowing forversatility in many different cell culture applications. The globularprotein, bovine serum albumin (BSA), is a major component of fetalbovine serum. The rich variety of proteins in fetal bovine serummaintains cultured cells in a medium in which they can survive, grow,and divide.

Apparently other properties of fetal serum and avian serum including eggproducts have not yet been subject to closer scrutiny. The presentinventor has however found that while the normal concentration of zincin the form of Zn(II) in human serum ranges from about 10 to about 20μmol/l (some sources report a range of 9 to 18 μmol/l, others a range of6-14 μmol/l) the concentration in animal sera, including fetal bovineserum, varies within a significantly wider interval. Analysescommissioned by the present inventor have revealed Zn(II) concentrationsranging from 0.5 μmol/l to 91.4 μmol/l.

The present inventor has also investigated the concentration of cadmiumin serum samples and found that the concentration was below thedetection limit of the methods used. As there are strong indicationsthat cadmium is a contributory factor in the development of cancer, theinventor postulates that it is important that the concentration ofcadmium in culture media is known, and preferably controlled, i.e.adjusted and/or maintained to/at a desired level, as changes inconcentration are likely to influence the proliferation of the cellsand/or tissue in the culture.

Cadmium is referred to as a non essential element, together with mercuryand lead, as these lack essential nutrient properties unlike othertransition metals such as copper, zinc, cobalt, manganese, andmolybdenum. These metals are generally considered as toxic to mammals,and they frequently imitate the action of an essential element in thebody, interfering with the metabolic processes, and causing illness.According to WHO information, it is established that cadmium exertstoxic effects on the kidney, the skeletal and the respiratory systems,and that it is classified as a human carcinogen. Cadmium is generallypresent in the environment at low levels. However, human activity hasgreatly increased those levels.

Cadmium can travel long distances from the source of emission byatmospheric transfer. It is readily accumulated in many organisms,notably mollusks and crustaceans. Lower concentrations are found invegetables, cereals and starchy roots. Human exposure occurs mainly fromconsumption of contaminated food, active and passive inhalation oftobacco smoke, and inhalation by workers in the non-ferrous metalindustry. The WHO calls for national, regional and global actions todecrease global environmental cadmium releases and reduce occupationaland environmental exposure.

The most dangerous characteristic of cadmium is that it accumulates inthe mammalian body, mainly in the liver and kidney. The concentrationsof cadmium in the liver and kidney are comparable after short-termexposure, but the kidney concentration tends to exceed the liverconcentration in the case of long- term exposure.

Reference levels for cadmium indicates that healthy non-smokers willhave less than about 5 nmol/l cadmium in their blood. This has beenconfirmed by tests commissioned by the inventor, showing concentrationsof 5.3 nmol/l. The cadmium concentration for habitual smokers isgenerally much higher, but frequently less than about 18 nmol/l. Acutetoxicity is observed at concentrations around 50 ng/ml.

Based on his experimental work, the present inventor makes available amethod for use in the prevention, treatment, and/or alleviation ofcancer in a mammal, wherein said mammal is subjected to a treatmentreducing the amount of cadmium and/or changing the proportion of cadmiumin relation to zinc in the body of said mammal. The significance of thisapproach is supported by the inventor's finding that the placentaprevents cadmium from passing into the fetus, ensuring the extremelyrapid, effective and simultaneously practically error free proliferationand differentiation of cells that takes place during the gestationperiod.

The above method can be applied to the prevention of metastasis andrecurrence of cancer and can preferably be performed in combination withsurgical removal of the tumor, preferably initiated already before thesurgical procedure and continued after said surgical removal of thetumor.

The above method can also be applied in combination with surgicalremoval of the tumor and the administration of one or more cytostaticdrug or drugs.

Similarly, the method according to the above embodiments can beperformed in combination with radiation therapy.

According to another embodiment, freely combinable with the aboveembodiments, the treatment further involves the administration of anon-toxic dose of a metal chosen from iron, selenium and zinc,preferably zinc.

According to another embodiment, freely combinable with the aboveembodiments, the treatment further involves a reduction of the amount ofcadmium or change of the proportion of cadmium in relation to zinc,wherein said reduction or change is performed by means of bloodtransfusion.

As an alternative or as a complement to blood transfusion, isolatedexosomes or an enriched exosome fraction can be used. The presentinventor has experimentally shown that exosomes can absorb zinc fromsurrounding serum. Based on this, it is suggested that the zinc contentof exosomes is increased by adding zinc to serum comprising exosomes,and then separating an exosome fraction “loaded” with zinc.

In this context it is very important to mention that smokers haveincreased concentrations of cadmium in their blood, and that smokerstherefore should be disqualified from donating blood, or at least thatblood from smokers should never be given to cancer patients.Accordingly, the present inventor suggests that blood donors are askedto report their smoking habits, and that blood obtained from smokingdonors is not used at all, used with restrictions, or treated so thatthe cadmium is removed, or the level of cadmium is reduced. In thealternative, it would be advantageous if donated blood was screened forcadmium content, similarly as is now done for HIV and hepatitis C, sothat it can be ensured that patients suffering from cancer, or patientswith impaired general health, suffering from or susceptible to disease,will not receive blood products which risk introducing cadmium in theirsystem.

According to another embodiment, freely combinable with the aboveembodiments, the reduction of the amount of cadmium or change of theproportion of cadmium in relation to zinc is performed by means ofextracorporeal dialysis.

The method according to the above embodiment, wherein the reduction ofthe amount of cadmium or change of the proportion of cadmium in relationto zinc is performed by means of dietary adjustments.

An advantage of the suggested approach is that the treatment isminimally invasive, and—in the case of zinc supplementation or dietaryadjustments—relatively safe and easy to implement. An additionaladvantage is that the suggested approach relies on the inherentcapability of repair and recovery of the mammalian body, which isdemonstrated by the practically flawless differentiation andproliferation of cells during fetal development. Other advantages willbe evident to a person skilled in the art upon study of the description,examples and claims.

In his experimental work, the inventor also found that an exosomefraction or pellet can be isolated from the serum byultracentrifugation. This opens possibilities not only to reduce theconcentration of Zn(II) but also to increase the same. The exosomepellet can be re-suspended and used to adjust the Zn(II) concentrationfor example by adding exosomes to fetal or avian serum, or to afertilized egg or to egg products.

In the case of vaccine production in fertilized eggs, an exosomefraction rich in Zn(II) can be introduced into the egg by microinjection or other known methods, simultaneously with or in associationwith the inoculation of the egg with the antigen. For the specific avianuse, and for addition to eggs, the exosome fraction is prepared fromblood from a bird or birds of the same species. This opens possibilitiesto optimize the production of antibodies in eggs, and also to adjust oroptimize vaccine production.

A first aspect of the invention relates to the importance of knowing thetrue Zn(II) concentration in a fetal serum product intended for use inmedicine, including diagnosis and therapy, as well as in the productionof reagents and agents for use in diagnosis and therapy, and inresearch.

Consequently, one embodiment of the invention concerns a method step inthe manufacture of serum products, in particular serum products intendedfor use in in vitro culture of mammalian cells or tissues, wherein theconcentration of Zn(II) is determined. Preferably the concentration ofZn(II) in the serum is adjusted to a desired interval, more preferablysignificantly reduced.

According to a preferred embodiment, the concentration of Zn(II) isadjusted to an interval of about 10 to about 500 μmol/l, preferablyabout 50 to about 200 μmol/l in the final serum product. According to analternative embodiment, the concentration of Zn(II) is adjusted to about50 μmol/l in the final product.

According to yet another alternative embodiment, the concentration ofZn(II) is adjusted to an interval of less than about 15 μmol/l,preferably less than about 10 μmol/l, more preferably less than about 5μmol/l in the final serum product.

According to an embodiment, the adjustment of the concentration ofZn(II) is performed by mixing fetal serum of at least two differentserum batches having different concentrations of Zn(II) in a ratio suchthat the final concentration of Zn(II) is in an interval of about 50 toabout 200 μmol/l in the final serum product.

According to an embodiment, the adjustment of the concentration ofZn(II) is performed by subjecting fetal serum to ultracentrifugation andremoving the formed pellet, or using other separation methods asapplicable.

According to an embodiment, freely combinable with all the aboveembodiments, the fetal serum is fetal serum from a mammal chosen fromcattle, pig, horse, goat, cat, dog, and rabbit. The currently mostfrequently used fetal serum is bovine fetal serum (BFS) also known asfetal calf serum (FCS)

Another aspect of the invention relates to the realization of thesignificance of exosomes present in fetal serum. Not only are thereindications (see the Examples section) that the exosomes and possiblyother micro and nanoparticles in the serum contain the main portion ofthe Zn(II) present in the serum, there are also indications thatexosomes play a significant role in the signaling between cells, and inthe proliferation of cells of different origin.

The present inventor has realized that the concentration of exosomes aswell as the concentration of Zn(II) needs to be known and preferablyadjusted to pre-set desired levels in order to guarantee reliable andconsistent result in manufacturing and research applications where fetalserum products are used.

Thus, according to another embodiment, also freely combinable with allthe above embodiments, the concentration of exosomes in the serum isdetermined, and the concentration in the final product is adjusted to avalue within a desired interval.

Yet another embodiment, also freely combinable with all the aboveembodiments, makes available a method step in the manufacture or thepreparation of a fetal serum product based on fetal serum of a specificspecies, wherein the diameter of the exosomes is determined, and/or theconcentration of Zn(II) in the exosomes in serum from said specificspecies is determined, whereupon the concentration of Zn(II) in thefinal product is adjusted a value within a desired interval.

An important aspect of the invention is thus the provision of new andimproved fetal serum products, inter alia a fetal serum productmanufactured according to a method or methods including one or more ofthe steps set out in the above embodiments.

One example is a fetal serum product having a concentration of Zn(II)adjusted to an interval of about 50- about 200 μmol/l. Another exampleis a fetal serum product having a concentration of Zn(II) adjusted toabout 50 μmol/l. A preferred example is a fetal serum product having aconcentration of Zn(II) adjusted to an interval of less than about 15μmol/l, preferably less than about 10 μmol/l, more preferably less thanabout 5 μmol/l in the final product.

An important aspect is that the concentration of Zn(II) should bedetermined and known before the product is used. One embodimenttherefore relates to a fetal serum product, preferably but notnecessarily manufactured using one or more of the above steps, whereinthe concentration of Zn(II) in said product is indicated on the packageor in the accompanying product data sheet.

Yet another aspect of the invention relates to methods for cell ortissue culture, regardless if the cell or tissue culture is part of aproduction method, a diagnostic method, therapy or research. Oneembodiment of this aspect is a method for in vitro cell or tissueculture using a culture medium containing a fetal serum product, whereinthe concentration of Zn(II) in the culture medium is determined, andadjusted to a desired level.

In the above embodiment, preferably the cells to be cultured are humancells, and the concentration of Zn(II) in the culture medium is adjustedto a value in the interval of 50- about 200 μmol/l, more preferably theconcentration of Zn(II) in the culture medium is adjusted to about 50μmol/l. More preferably the concentration of Zn(II) in the culturemedium is adjusted to a value within an interval of less than about 15μmol/l, preferably less than about 10 μmol/l, more preferably less thanabout 5 μmol/l in the final product/l.

Another aspect of the invention relates to methods for in vitro cell ortissue culture using a culture medium containing a fetal serum product,wherein the concentration of Zn(II) in the culture medium is determined,adjusted to a selected level, and maintained at said level during theduration of the cell or tissue culture and/or when repeating saidculture.

Yet another aspect of the invention concerns avian serum products, andin particular egg white and egg yolk. The present inventor has foundthat eggs contain higher amounts of Zn(II) than mammalian serum. Theconcentration of Zn(II) in egg yolk can be in the interval of 50-70micro molar. The inventor postulates that it is of considerablesignificance that the concentration of Zn(II) is known in order toensure repeatability of the culture methods where avian serum or eggproducts are used. Further, it is also preferred that the concentrationof Zn(II) is adjusted to a desired level.

An embodiment of the invention therefore relates to avian serum productsmanufactured according to the methods or method steps disclosed herein,mutatis mutandis, i.e. with necessary modifications.

One embodiment is thus an avian serum product having a concentration ofZn(II) adjusted to an interval of about 50- about 200 μmol/l. Preferablysaid avian serum product has a concentration of Zn(II) adjusted to about50 μmol/l.

According to a preferred embodiment, the avian serum product has aconcentration of Zn(II) adjusted to an interval of less than about 15μmol/l, preferably less than about 10 μmol/l, more preferably less thanabout 5 μmol/l in the final product.

A particular embodiment is an avian serum product wherein theconcentration of Zn(II) in said product is indicated on the package orin the accompanying product data sheet.

Another embodiment of said aspect is a method for in vitro cell ortissue culture using a culture medium containing an avian serum product,wherein the concentration of Zn(II) in the culture medium is determined,and adjusted to a desired level. Preferably the concentration of Zn(II)in the culture medium is adjusted to a value in the interval of 50-about 200 μmol/l. More preferably the concentration of Zn(II) in theculture medium is adjusted to about 50 μmol/l.

Further, according to an embodiment freely combinable with the aboveaspects and embodiments, the cells to be cultured are human cells, andthe concentration of Zn(II) in the culture medium is adjusted to a valuewithin an interval of less than about 15 μmol/l, preferably less thanabout 10 μmol/l, more preferably less than about 5 μmol/l in the finalproduct/l. In the case of eggs, the concentration of Zn(II) can beinfluenced by adjusting the composition and amount of feed given to thebirds, e.g. hens or ducks.

Another aspect is a novel method for in vitro cell or tissue cultureusing a culture medium containing an avian serum product, wherein theconcentration of Zn(II) in the culture medium is determined, adjusted toa selected level, and maintained at said level during the duration ofthe culture and/or when repeating said culture.

Interestingly, when embryonic stem cells are cultivated in the absenceof cadmium, rapid growth and differentiation is achieved without anysigns of tumorigenesis. However, when immortalized cell lines, tumorcell lines, are cultivated, this is conventionally done in the presenceof 10% fetal bovine serum, which has now been shown—by the inventor—tocontain varying amounts of cadmium.

In the light of these results, it seems very plausible that the capacityof the placenta to block the cadmium ions from passing into embryonaltissue has significant importance. The present inventor is not inposition to definitely postulate which are the most deleteriousreactions in which cadmium is a key factor, but it is contemplated thatthe cadmium ion disturbs the balance between the action of phosphatasesand kinases, which together regulate the phosphorylation state of manyimportant signaling molecules and cellular processes implicated in cellgrowth, cellular differentiation, mitotic cycles, oncogenictransformation and receptor endocytosis.

Another theory proposed by the present inventor is that cadmium takesthe place of calcium, in reactions involving cadhedrins, a group oftransmembrane proteins known to play important roles in cell adhesion,the separation of different tissue layers and cell migration.Interestingly, malfunctioning of the epithelial cadhedrin—catenincomplex has been associated with tumor metastasis. The inventorspeculates that it is the similarity between the ion radius of the Ca2+ion (114 m) and the Cd2+ ion (109 pm) that makes this possible.

The inventor contemplates that the above effects directly influence anddisturb the function of the tight junction, for example making itpossible for cancerous cells to leave diseased tissue, travel in theblood stream and lymphatic system, and entering healthy tissues. In thiscase, increased concentration of cadmium could directly promotemetastasis of cancer.

Another theory suggested by the present inventor is that the presence ofthe metals cadmium and zinc, their concentrations and the ratio betweenthem, directly influences the functioning of the enzymes involved in DNAreplication as well as in the enzymatic correction of replicationerrors.

EXAMPLES Example 1 Analysis of Zn(II) Concentration in Sera of DifferentOrigin

The present inventor has commissioned analyses of different batches ofsera, and also sera from different animals. These analysis of differentbatches of FBS has revealed significant variations in the concentrationof Zn(II) between batches. The analysis of sera from different animalshas revealed significant variations between animals.

The analyses were performed at an accredited laboratory, using atomicabsorption spectroscopy (AAS) and standard samples obtained fromPerkin-Elmer (Norwalk, Conn., USA). The results are shown in Table 2.

TABLE 2 Concentration of Zn(II) in serum samples Serum Concentration ofZn Sample μmol/l FBS (USA) 1 56.1 FBS (USA) 2 91.4 FBS inactivated 47.5FBS (Non-US) 26 (Sigma Lot No. 103 M 3396/F 7524) FBS 37.0 FBS (US) 33(Sigma Lot No. 074 M 3328) FBS 60.9 Newborn Calf Serum (US) 11 (SigmaN-4762 14 A 316) Iron-fortified Calf Serum from Formula 22 fed animals(US) Sample 1 (Sigma C 8066 11 M 026) Iron-fortified Calf Serum fromFormula 23 fed animals (US) Sample 2 (Sigma C 8066 11 M 026) Newborncalf serum (NZ) 17 (GIBCO 16010 NBCS Ref. No. 1060??- 17 167) BovineSerum (NZ) 17 (GIBCO Lot. No. 137 2691/26170 035) Newborn Calf Serum(NZ) 18 Heat inactivated (GIBCO Ref: 26010-066, Lot. No. 1169682) BovineSerum (NZ) 14 (GIBCO Ref: 16170-86, Lot. No. 1610982) FBS (ZA) 24 (34)(GIBCO REF 1o 270-098, Lot No. 42 F 035 1 K) FBS (USA) 27 GIBCO Ref.26140 087, Lot.1680 777) FBS (AU) 25.8 (GIBCO Ref. 10099-133, Lot.No.1633098) FBS (AU) 25.7 Heat-inactivated (GIBCO Ref. 10100-139 Lot No.1688877 S) FBS (US) 3 56.1 Goat serum (NZ) 12.2 GIBCO Ref. 16210-064,Lot No. 1517965) Rabbit serum (US) 27.8 (GIBCO Ref. 16120-099, Lot. No.1705973) Horse serum (NZ) 15.8 (15.6) (GIBCO Ref. 16050-130, Lot No.1486538) Chicken serum (NZ) 78.2 Porcine serum (NZ) 22.1 Ref. 26250-084,Lot No. 161 4268 Lamb serum (NZ) 15.6 (GIBCO Ref. 16070-096, Lot No.1517956)

In total, the analysis show that there are indeed considerablevariations in the concentration of Zn(II) in serum of different origin,both geographical origin, and from different animal species. Serum andin particular fetal calf serum is a standard ingredient in cell culture,frequently added in an amount of 10% to the culture medium.Nevertheless, it is very seldom if ever that one sees an indication ofwhich serum has been used, or any information about the properties ofthis serum, for example with regard to the concentration of metal ions.

As the Zn(II) ion has a fundamental role in the cell metabolism, thepresent inventor concludes that it is of considerable significance thatthe concentration of Zn(II) is known, and adjusted to a known range. Thepresent inventor suggests that the variation in the concentration ofZn(II) is a considerable source of error both in experiments and in theproduction of biopharmaceuticals using serum supplemented growth media.It is consequently preferred that the concentration of Zn(II) isadjusted so, that the final concentration in the cell culture mediumfalls within the normal concentration of zinc in the form of Zn(II) inhuman serum, i.e. in a range from about 10 to about 20 μmol/l.Preferably the same concentration is ascertained in all experiments, andin all production batches, in order to guarantee reliable results and aneven quality of products.

Example 2 Analysis of Cd Concentration in Fetal Serum Samples

The inventor also commissioned the analysis of cadmium in a number ofserum samples. To the best of his knowledge, cadmium has no knownbeneficial function in the human body. There however existsepidemiological evidence showing a significant association betweencadmium in human serum, and cancer.

The concentration of cadmium was determined at an accredited laboratory(VITA Laboratorio, VITA-Terveyspalvelut, Helsinki, Finland), usingstandard procedures and an atomic absorption spectroscopy (AAS)apparatus from Perkin-Elmer (Norwalk, Conn., USA). The results indicatethat fetal serum is free of cadmium or only contains cadmium in levelsbelow the detection limit of the analysis method, here 4.5 μmol/l. Theresults are shown in Table 3.

TABLE 3 Comparison of Zn(II) and Cd concentration in serum samplesConcentration of Zn(II) and Cd Zn(II) Cd Sample ID μmol/l nmol/l 2 33<4.5 3 46 <4.5 12 34 <4.4 13 34 <4.4 14 74 <4.5 15 44 <4.5

It is generally held that a non-smoker who has not been exposed tocadmium, should exhibit concentrations below 5 nmol/l or less. A smokerwill exhibit higher concentrations, but less than 18 nmol/l. 50 nmol/lis a threshold at which medical treatment needs to be initiated(information supplied by the analyzing company, VITA Laboratorio).

The above result confirms the threshold for healthy, non-smokingindividuals. It remains to analyze the blood of habitual smokers, and itwould be of interest to see how the concentration of cadmium changeswith time, in order to determine for example for how long a personshould be disqualified as a blood donor after having stopped smoking.

The experiments also show that it is feasible to screen donor blood withregard to the content of cadmium, a procedure that the present inventorstrongly advocates.

Example 3 Separation of Particles From Sera of Different Origin, FirstTrial

The present inventor also commissioned a study where cell free serumsamples were subjected to ultracentrifugation. The study was performedat VTT Technical Research Centre of Finland Ltd, Espoo, Finland inNovember 2015. An ultracentrifuge (Beckman Optima™ LE-BOK) was usedaccording to the manufacturer's instructions. The objective of the studywas to test if particles with a diameter less than 200 nm (0.2 μm) couldbe separated from cell free serum samples using ultracentrifugation.

A total of 8 samples were supplied in duplicate and stored at −20° C.according to the inventor's instructions. A stabilizing reagent (DTT,DL-dithiothreitol) was also supplied by the inventor, and stored at +4°C. The samples were ultracentrifuged at 150 000×g for 20 h at +4° C. Onetest tube broke during the ultracentrifugation, but with exception forthis tube, the test showed that a pellet was formed in all the testtubes. It was noted that in some samples, two pellets were formed, onethat was described as “loose” and another, described as glue-like anddifficult to dissolve.

Example 4 Separation of Particles from Sera of Different Origin, SecondTrial

The present inventor commissioned a second study where cell free serumsamples were subjected to ultracentrifugation. The study was performedat VTT Technical Research Centre of Finland Ltd, Espoo, Finland inDecember 2015. An ultracentrifuge (Beckman Optima™ LE-BOK) was usedaccording to the manufacturer's instructions. The objective of the studywas to test if particles with a diameter less than 200 nm (0.2 μm) couldbe separated from cell free serum using ultracentrifugation.

A total of 8 samples were supplied in duplicate and stored at −20° C.according to the inventor's instructions. A stabilizing reagent (DTT,DL-dithiothreitol) was also supplied by the inventor, and stored at +4°C.

Four serum samples were thawed on ice, and the volume measured. Eachsample was divided in two portions of equal volume, and diluted with1×PBS to a final volume of 10 ml. The samples were then filtered using0.2 μm syringe filters supplied by the inventor.

In a first test run, one portion of each sample was transferred toindividual ultracentrifuge tubes. In a second test run, the samples weretreated with DTT according to the inventor's instructions prior toultracentrifugation. All samples were treated by ultra centrifuging at150 000×g for 20 h at +4° C. A pellet could be detected in all tubes.

In the first test run, a loose pellet was seen in all samples, and inone sample an additional, small and denser pellet was observed. Thesupernatants were collected from each sample, taking great care not toinclude any of the pellet. DTT was added to the pellets, and the sampleswere incubated in 37° C. and vortexed every two minutes. During thistreatment, the samples formed a gel. This gel was however dissolved bythe addition of 1×PBS to a total volume of 10 ml for each sample. There-suspended pellets were centrifuged once more, at 150 000×g for 1 hand at a temperature of 30-37° C. There were problems reaching thedesired temperature of 37° C. until the later part of the centrifugationtime (1 h). In each sample, the second centrifugation resulted in atranslucent, solid pellet with a faint red color, and none of the loosepellets reported in Examples 2 and 3 above.

In the second test run, subjected to ultracentrifugation using the sameconditions, the resulting pellets had a different appearance. They werelarger and appeared to consist of two layers, with an upper, larger andlooser pellet, and a lower reddish and hard pellet.

In both test runs, there were difficulties in dissolving the hardpellets, so these were transferred to test tubes supplied by theinventor using a shortened 5 ml pipette tip and possibly remainingpellet fragments were collected with a sterile loop. According to theinventor's instructions, 2 drops of 65% nitric acid was added to eachtube to promote dissolution. The samples were returned to the inventorfor further analysis.

Example 5 Analysis of Exosomes Isolated from Fetal Calf Serum Samples

The pellets obtained in Examples 3 and 4 are washed in PBS and theircontent of exosomes can be analyzed qualitatively or quantitativelyusing methods known in the art, e.g. using flow cytometry analysis(FACS), transmission electron microscopy (TEM) analysis, immunogoldstaining, or NanoSight LM10 (NanoSight Ltd) analysis. Similarly, theconcentration of exosomes in fetal serum can be determined by methodsknown to a skilled person. The samples are preferably subjected to afiltration pre-treatment removing larger particles.

Example 6 Analysis of Zn(II) Concentration

The pellets obtained in Examples 2 and 3 were washed in PBS and theZn(II) concentration measured by atomic absorption spectrometry using aPerkin Elmer Atomic Absorption apparatus (AAS). The results are shown inTable 4 below:

TABLE 4 Concentration of Zn(II) in samples of serum before and afterultracentrifugation Concentration of Zn(II) in μmol/l Type of sampleSample ID Serum Pellet Supernatant 12 43.0 26 53.1 27 53.4 201  48.412/1 39 1.3 26/1 50 0.4 27/1 50.1 0.7 201/1  45.2 1.4 12/2 41.5 0.5 26/252 0.0 27/2 52.1 1.0 201/2  47.1 0.0

The analysis shows that the ultracentrifugation was successful inreducing or in some samples, eliminating Zn(II) from the supernatant.

The above examples indicate that Zn(II) is contained in the exosomespresent in cell free serum, and also that the concentration of Zn(II) inserum can be significantly reduced or even eliminated usingultracentrifugation or possibly other separation methods. In themajority of the tests, the concentration of Zn(II) in the supernatantwas reduced to about 1 μmol/l or less.

The general understanding has hitherto been that metals in serum arebound to albumin, but the current preliminary experiments indicate thatat least a portion of the Zn(II) is bound to particulate matter, e.g.exosomes, in serum, and that it can be concentrated and removed forexample by ultracentrifugation.

Example 7 Whole Body Autoradiography Investigating the Enrichment of Cdand Zn Isotopes

The present inventor commissioned studies where the function of theplacenta was investigated using radioactive isotopes of cadmium andzinc. Pregnant female mice were injected intravenously with 8 pc of¹⁰⁹CdCl₂ obtained from Philips Ltd., Eindhoven, Holland. The injectionof isotope was made into the tail vein according to standard practice.The mice were injected so that the day of sacrifice coincidedapproximately with the 18th day after conception, determined by thepresence of a vaginal plug after mating. The mice were sacrificed underether anesthesia by immersion in a mixture of acetone and liquid carbondioxide (about −80 C). The mice were then sagittally sectioned in a coldroom at −10 C according to standard practice, and the sections obtainedwere affixed to cellulose tape.

Each section was then apposed to X-ray film together with an isotopereference standard. The sections and films were kept at −10 C untilexposure was complete. The determination of the order of cadmium andzinc concentration in different organs was made through densitometriccomparison of the autoradiographic exposure caused by the organs,compared to the reference standard.

The autoradiography studies showed a significant difference in thebehavior of these two metals. While Zn passed through the placenta andwas enriched in the fetal tissue, Cd did not pass the placental barrier.The mechanism behind this is not fully understood, but the presentinventor contemplates that metallothionein proteins have an importantfunction in binding cadmium and preventing it from passing into thefetus.

This theory is supported by the results of a separate analysis of thecadmium concentration in embryonal tissues from mice embryos,commissioned by the inventor. The results showed that the concentrationof cadmium was very low, ranging from below about 4.4 nanomol/l to about5.3 nanomol/l whereas the concentration of zinc in the same samples wasin the range of 30-40 micromol/l. Further analytical work is ongoing.

Related studies commissioned by the inventor have shown that theexosomes in fetal calf serum are capable of absorbing zinc when zinc isadded to said serum. Based on this, the present inventor postulates thatthe exosomes are similarly capable of absorbing cadmium. There istherefor a risk that donor blood and blood products may increase thecadmium load in a patient undergoing cancer treatment, and receivingblood transfusions or the administration blood products as part of thetreatment, or for mitigating side effects of the treatment, such asanemia, compromised immune defense etc. In order to eliminate the riskthat donor blood containing cadmium, or blood products containingcadmium are given to the patient, with possible negative consequencesfor example on metastasis, the inventor proposes a screening step ofdetermining the cadmium content in donor blood and discarding blood andblood products with a cadmium content exceeding the levels normallyencountered in healthy subjects. Preferably the level of cadmium shouldbe zero or as low as possible, and for some products this can beachieved by separating the exosome fraction and possibly replacing itwith uncontaminated exosomes from a compatible source. The easiestapproach to minimizing the concentration of cadmium in donor blood andproducts made thereof would be to request blood donors to indicate ifthey are smokers or not, and either disqualify them as donors, or markthe blood with an indication that it mustn't be administered to cancerpatients.

In summary, the present inventor postulates that the capability of theplacenta to prevent cadmium from passing into fetal tissues is of greatsignificance for the rapid and practically error-free proliferation anddifferentiation of cells that takes place during gestation.

Conversely, when the mammalian organism is subjected to cadmium postpartum and all through life, the disrupted balance between zinc andcadmium is likely to be a causative factor behind different disease,such as but not limited to cancer.

The findings of the present inventor form the basis for a new approachto the production of blood and serum products for use both in research,biotech production and in therapy.

Listing of Embodiments

-   1. A method in the manufacture of serum products, in particular    fetal serum products, wherein the concentration of Zn(II) in the    serum is determined and adjusted to a desired, specific value.-   2. A method step in the manufacture of serum products, wherein the    concentration of Zn(II) in the serum is determined, and the    concentration adjusted to a desired interval in the final product.-   3. The method according to any one of embodiments 1 and 2, wherein    the concentration of Zn(II) is adjusted to an interval of about 50    to about 200 μmol/l in the final product.-   4. The method according to embodiment 1, wherein the concentration    of Zn(II) is adjusted to about 50 μmol/l in the final product.-   5. The method according to any one of embodiments 1 and 2, wherein    the concentration of Zn(II) is adjusted to an interval of less than    about 15 μmol/l, preferably less than about 10 μmol/l, more    preferably less than about 5 μmol/l in the final product.-   6. The method according to any one of embodiments 1 and 2, wherein    the adjustment of the concentration of Zn(II) is performed by mixing    fetal serum of at least two different serum batches having different    concentrations of Zn(II) in a ratio such that the final    concentration of Zn(II) is in an interval of about 50 to about 200    μmol/l in the final product.-   7. The method according to any one of embodiments 1 and 2, wherein    the adjustment of the concentration of Zn(II) is performed by    subjecting fetal serum to ultracentrifugation and removing the    formed pellet.-   8. The method according to any one of embodiments 1 and 2, wherein    the fetal serum is fetal serum from a mammal chosen from cattle,    pig, horse, goat, cat, dog, and rabbit.-   9. A method step in the manufacture or the preparation of fetal    serum products, wherein the concentration of exosomes in the serum    is determined, and the concentration in the final product is    adjusted to a value within a desired interval.-   10. A method step in the manufacture or the preparation of a fetal    serum product based on fetal serum of a specific species, wherein    the diameter of the exosomes is determined, and/or the concentration    of Zn(II) in the exosomes in serum from said specific species is    determined, whereupon the concentration of Zn(II) in the final    product is adjusted a value within a desired interval.-   11. A serum product, preferably a fetal serum product, manufactured    according to the method of any one of embodiments 1-10.-   12. A serum product, preferably a fetal serum product, having a    concentration of Zn(II) adjusted to an interval of about 50- about    200 μmol/l.-   13. A serum product, preferably a fetal serum product, having a    concentration of Zn(II) adjusted to about 50 μmol/l.-   14. A serum product, preferably a fetal serum product, having a    concentration of Zn(II) adjusted to an interval of less than about    15 μmol/l, preferably less than about 10 μmol/l, more preferably    less than about 5 μmol/l in the final product.-   15. A serum product according to any one of embodiments 11 to 14,    wherein the concentration of Zn(II) in said product is indicated on    the package or in the accompanying product data sheet.-   16. A method for in vitro cell or tissue culture using a culture    medium containing a fetal serum product, wherein the concentration    of Zn(II) in the culture medium is determined, and adjusted to a    desired level.-   17. The method according to embodiment 16, wherein the cells to be    cultured are human cells, and the concentration of Zn(II) in the    culture medium is adjusted to a value in the interval of 50- about    200 μmol/l.-   18. The method according to embodiment 16, wherein the cells to be    cultured are human cells, and the concentration of Zn(II) in the    culture medium is adjusted to about 50 μmol/l.-   19. The method according to embodiment 16, wherein the cells to be    cultured are human cells, and the concentration of Zn(II) in the    culture medium is adjusted to a value within an interval of less    than about 15 μmol/l, preferably less than about 10 μmol/l, more    preferably less than about 5 μmol/l in the final product /I.-   20. A method for in vitro cell or tissue culture using a culture    medium containing a fetal serum product, wherein the concentration    of Zn(II) in the culture medium is determined, adjusted to a    selected level, and maintained at said level during the duration of    the culture and/or when repeating said culture.-   21. An avian serum product, wherein manufactured according to the    method of any one of claims 1-10 mutatis mutandis.-   22. An avian serum product having a concentration of Zn(II) adjusted    to an interval of about 50- about 200 μmol/l.-   23. An avian serum product having a concentration of Zn(II) adjusted    to about 50 μmol/l.-   24. An avian serum product having a concentration of Zn(II) adjusted    to an interval of less than about 15 μmol/l, preferably less than    about 10 μmol/l, more preferably less than about 5 μmol/l in the    final product.-   25. An avian serum product according to any one of embodiments 11 to    14, wherein the concentration of Zn(II) in said product is indicated    on the package or in the accompanying product data sheet.-   26. A method for in vitro cell or tissue culture using a culture    medium containing an avian serum product, wherein the concentration    of Zn(II) in the culture medium is determined, and adjusted to a    desired level.-   27. The method according to embodiment 26, wherein the cells to be    cultured are human cells, and the concentration of Zn(II) in the    culture medium is adjusted to a value in the interval of 50- about    200 μmol/l.-   28. The method according to embodiment 26, wherein the cells to be    cultured are human cells, and the concentration of Zn(II) in the    culture medium is adjusted to about 50 μmol/l.-   29. The method according to embodiment 26, wherein the cells to be    cultured are human cells, and the concentration of Zn(II) in the    culture medium is adjusted to a value within an interval of less    than about 15 μmol/l, preferably less than about 10 μmol/l, more    preferably less than about 5 μmol/l in the final product /I.-   30. A method for in vitro cell or tissue culture using a culture    medium containing an avian serum product, wherein the concentration    of Zn(II) in the culture medium is determined, adjusted to a    selected level, and maintained at said level during the duration of    the culture and/or when repeating said culture.-   31. A method in the prevention, treatment, and/or alleviation of    cancer in a mammal, wherein said mammal is subjected to a treatment    reducing the amount of cadmium or changing the proportion of cadmium    in relation to zinc in the body of said mammal.-   32. The method according to the above embodiment, in combination    with surgical removal of the tumor.-   33. The method according to the above embodiment, in combination    with surgical removal of the tumor and the administration of one or    more cytostatic drug or drugs.-   34. The method according to the above embodiment, in combination    with radiation therapy.-   35. The method according to the above embodiment, further involving    the administration of a non-toxic dose of a metal chosen from iron,    selenium and zinc, preferably zinc.-   36. The method according to the above embodiment, wherein the    reduction of the amount of cadmium or change of the proportion of    cadmium in relation to zinc is performed by means of blood    transfusion.-   37. The method according to the above embodiment, wherein the    reduction of the amount of cadmium or change of the proportion of    cadmium in relation to zinc is performed by means of extracorporeal    dialysis.-   38. The method according to the above embodiment, wherein the    reduction of the amount of cadmium or change of the proportion of    cadmium in relation to zinc is performed by means of dietary    adjustments.-   39. A method step in the handling of donor blood, wherein the    cadmium concentration in the blood is determined, and blood    containing elevated concentrations of cadmium is disqualified for    human use.-   40. A method step in the collection of donor blood, wherein the    donor is asked to indicate if he/she is a smoker or has been    habitually smoking but stopped, in which case the donated blood is    subjected to analysis for the cadmium content, and wherein blood    containing elevated concentrations of cadmium is disqualified for    human use.-   41. A step in the treatment of cancer, wherein the cadmium level in    the blood of the patient is determined, and an increased level    compared to levels typical for a healthy population, is noted as a    factor which potentially aggravates the disease and which motivates    actions to lower the concentration of cadmium as a part of the    treatment of cancer.

Without further elaboration, it is believed that a person skilled in theart can, using the present description, including the examples, utilizethe present invention to its fullest extent. Also, although theinvention has been described herein with regard to its preferredembodiments, which constitute the best mode presently known to theinventors, it should be understood that various changes andmodifications as would be obvious to one having the ordinary skill inthis art may be made without departing from the scope of the inventionwhich is set forth in the claims appended hereto.

Thus, while various aspects and embodiments have been disclosed herein,other aspects and embodiments will be apparent to those skilled in theart. The various aspects and embodiments disclosed herein are forpurposes of illustration and are not intended to be limiting, with thetrue scope and spirit being indicated by the following claims.

REFERENCES

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What is claimed is:
 1. A method for processing donor blood, comprisingcollecting blood from a donor; determining a concentration of cadmium inthe collected blood; and disqualifying the collected blood for human useif the collected blood has a concentration of cadmium greater than apredetermined threshold.
 2. The method according to claim 1, furthercomprising asking the donor if he/she is a smoker or has been habituallysmoking but stopped, wherein the determining step carried out inresponse to a positive indication returned from the donor.
 3. The methodaccording to claim 1, wherein human use is defined as the administrationof a blood transfusion to a cancer patient as part of a cancertreatment, or for mitigating a side effect of a cancer treatment,
 4. Themethod according to claim 1, wherein the concentration of cadmium isdetermined using atomic absorption spectroscopy.
 5. The method accordingto claim 1, wherein donor blood is disqualified for human use when theconcentration of cadmium is above 5 nmol/l.
 6. A method for themanufacture of a serum product, comprising determining a concentrationof Zn(II) in a serum batch, and adjusting the concentration in the serumbatch to a desired interval.
 7. The method according to claim 6, whereinthe concentration of Zn(II) is adjusted to an interval of about 50 toabout 200 μmol/l.
 8. The method according to claim 6, wherein the serumproduct is a serum supplemented culture medium, and the concentration ofZn(II) in the serum supplemented culture medium is adjusted to aninterval of about 10 to about 20 μmol/l.
 9. The method according toclaim 6, wherein the concentration of Zn(II) is determined using atomicabsorption spectroscopy.
 10. The method according to claim 6, whereinthe concentration of Zn(II) is adjusted by removal or addition ofexosomes.
 11. The method according to claim 10, wherein an exosomefraction is concentrated and removed by ultracentrifugation, and saidexosome fraction is used to adjust the concentration of Zn(II) in theserum product.
 12. The method according to claim 6, wherein theconcentrations of Zn(II) and Cd in said product are determined, andindicated on a package for the product or in an accompanying productdata sheet.
 13. A serum product wherein the concentration of Zn(II) hasbeen determined, and adjusted to an interval of about 50 to about 200μmol/l.
 14. The serum product according to claim 13, wherein the sourceof serum is fetal serum.
 15. The serum product according to claim 13,wherein the source of serum is donor blood.
 16. The serum productaccording to claim 13, wherein the concentrations of Zn(II) and Cd insaid product have been determined, and are indicated on a package forthe product or in an accompanying product data sheet.
 17. A serumproduct wherein the serum product is a serum supplemented culturemedium, and the concentration of Zn(II) in the serum supplementedculture medium is adjusted to an interval of about 10 to about 20μmol/l.
 18. The serum product according to claim 17, wherein the sourceof serum is fetal serum.
 19. The serum product according to claim 17,wherein the source of serum is donor blood.
 20. The serum productaccording to claim 17, wherein the concentrations of Zn(II) and Cd insaid product have been determined, and are indicated on a package forthe product or in an accompanying product data sheet.